Based on L. Frank Baum's Oz novels, Oz the Great and Powerful serves as a prequel to Baum's 1900 introductory novel The Wonderful Wizard of Oz and a homage to the 1939 MGM film, The Wizard of Oz. Set 20 years before the events of both sources, Oscar Diggs arrives in the Land of Oz where he discovers three witches; Theodora, Evanora and Glinda. Oscar is then inclined to restore order in Oz, while struggling to resolve conflicts with the witches and himself.